High Idle

[KooK]

I'm getting a really high idle when I start my 91 Eclipse GS Cold. When it first starts its at 2,500rpm but it goes back down to 1000 give or take 100 depending on its mood.

Anybody have a guess? Thanks in advance!

 

[fast_talon]

I would adjust your BISS to see if you can lower the idle when cold, but when the car is warmed up still idle ~ 900-1000 rpm. My car has had this problem but it will idle correctly after a few minutes of ideling.

 

[toshi128]

Same here, my car idles at about 1500 - 2500 rpm when i start it cold... then it goes down to between 750-900 rpm after warming up...

 

[laserblue]

Common stuff....... When the engine is cold, the water circulates [it always does, hot or cold] around the fast idle valve which 'feels' the cold water and opens to let more air in [bypassing the throttle plate]. This makes the idle faster which is needed in a cold engine to assist warm-up. As the water grows hot the valve slowly closes and the rpm's decrease. This mysterious valve can get a little flaky and stay open too long.... or a little more air gets in than is supposed to... or whatever............ and the result is fast idle; Faster idle for a longer time than it used to be. Playing with the BISS is a fudge to get the idle down a bit, but it's not the answer to the problem, which is usually not much of a problem at all.
I read in a post somewhere that there is a 'wax pellet' in this fast idle valve. The wax melts with hot temp and that is what makes the valve close. With age this wax 'mechanism' doesn't work so well.
DOES ANYONE HAVE BETTER INFO AND ADVICE???

 

[KooK]

Well, the only reason why I brought this question up is because when I start my Talon, it'll idle at 1500 max and drop down to 1000-900rpm. I get in the Eclipse and its like, holy crap! I mean I get people that look at me when I first start my car because its like, kid... duh, get off the throttle. Then I walk out and they just kinda look at the car.

You should have seen them before I cleaned my TB!

 

[laserblue]

I know, I know. ---- My car does this idle surge thing for 3 minutes when I start it up cold. People gather around to point and stare!!

 

[KooK]

Crap, I mean, I wasn't talking about surging, I'm talking about it stays at the high idle until its warm, then it drops back down to a normal 1000rpm.

When I cleaned the TB the surge stopped, but I did have that problem.

 

[laserblue]

Yes, I know.... I was just saying that people look at my car funny also.
My whole story is... At cold start my idle is up at about 2000 rpm. After a minute or so it starts to idle surge. Then slowly the surge cycle slows down and the idle oozes down below 1500 rpm, so the surge stops. Then finally the idle decreases to normal. THEN the people stop pointing and go away!
Anyway, up in Post 4 I tried to give an explanation of why this can happen. The fast idle valve is usually the culprit. What I would like to know is why the fast idle is so fast in some cars and not so fast in others??????? You know, what parts have changed over the years that now makes the fast idle a fast-fast idle?